The game already has many options for that you death loving deviant, As a matter of fact the game needs options for disabling deaths, especially the one caused by old age. The one the game currently had is simply not good enough.
The hero death option on disable mode should also disable aging as well; in this mode the character creation menu should have additional options such as editing the character's body parts similar in function to the Detailed Character Creation mod, including the option to edit the player character's age to his/her liking.
The lords at the start of the game and lords for newly spawned clans should have a preset age, and the NPC children from these lords will have a short period of childhood before becoming adults, they too will also have a preset age between 21 to 51.
As for the player's NPC children; they function similarly to the NPC lord's children however the difference is that the age (and their appearance) of your NPC children can be edited from their character profile once they are old enough to fight alongside you.
For those 'special people' who don't like the above suggestions; All you have to do is enable death in the options menu, simple as that.